RU2355777C2 - Method and melting mill for receiving of steel with high content of manganese and low content of carbon - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field, particularly it relates to the method and facility for receiving of steel with high content of manganese and low content of carbon from liquid cast iron or liquid steel and slag-forming. Character of the invention is that it is implemented feeding of liquid ferromanganese with carbon content approximately 6% and liquid steel with carbon content approximately 0.1% or liquid cast iron and slag-forming into converter for finishing of ferromanganese. Then by means of combined oxygen blow through top and bottom lances content of carbon in melt is reduced preliminary up to 0.7-0.8%. Deal of cold product of previous melting is used in the capacity of cooler, and by means of continuous oxygen blow through bottom lances content of carbon is reduced approximately up to 0.05-0.1%.

EFFECT: receiving of high-manganese steel with low carbon content with low expenditures.

4 cl, 2 dwg

Description

The invention relates to a method and a smelter for producing steel with a high manganese content and a low carbon content from molten iron or molten steel and using slag-forming materials.

The production of steel with a high manganese content in metallurgical production today is based on the electric steelmaking process with scrap processing (report at the metallurgical forum in Leoben, 2003, Authors Gigacher, Doppler, Bernard Krieger, published in BHM, Bd. 148, Nr. 11, 2003, p. 460-465, XP009063529). During the production process, manganese sources in the form of ferroalloys are planted in the melt. This raises the problem that ferromanganese (FeMn) with a low carbon content is about 300 times more expensive than a similar high carbon ferroalloy. Low carbon ferromanganese is nevertheless best suited for manufacturing applications.

The production of steel with a high manganese content in a metallurgical unit other than an electric furnace is limited by the fact that large quantities of manganese are slagged when the melt is purged with oxygen, since oxygen has a higher affinity for manganese during decarburization of steel. So far, the choice of the production route with the participation of the converter is associated with high slagging of manganese and, accordingly, a low manganese content in steel at the level of 16-17%.

The production of steel with a high content of manganese and a low carbon content in the electric furnace is associated with many problems: in the arc region at temperatures reaching 3000 ° C, intense evaporation of manganese takes place. Requires the use of expensive scrap containing minimal amounts of contaminants. In addition, expensive low carbon ferroalloys should be used.

The basis of the invention is the task of reducing the disadvantages associated with the production line, which includes metallurgical units other than the electric furnace, while using cast iron and Fe-Mn molten liquid, high-manganese steel with a low carbon content is obtained.

The problem is solved according to the invention due to the fact that the process is carried out by feeding liquid ferromanganese with a carbon content of about 6% and liquid steel with a carbon content of about 0.1% to a converter for refining ferromanganese together with the required amount of slag-forming materials, while using combined blowing with oxygen through the upper and lower tuyeres, the carbon content in the melt decreases to about 0.7-0.8%, and a certain amount of the cold product of the previous melting is used as aditelya, and thus by continuous blowing oxygen through bottom tuyeres carbon content is reduced to about 0.05-0.1%. Due to coolers and the process of refining the melt from carbon at relatively low temperatures and below the surface of the melt mirror, the evaporation of manganese is reduced. The use of carbon ferromanganese as a source of manganese provides an efficient process for the production of steel with a high manganese content. The manganese content in steel can be increased up to 25-30%. The use of cast iron facilitates the implementation of stringent requirements regarding the content of copper and other contaminants. The production of steel with a high content of manganese and other additives is possible within the framework of integrated steelmaking. Impurities such as copper, zinc, tin, molybdenum, tungsten and others are not introduced into steel together with scrap metal.

Preferably, if partial pressure is reduced by blowing oxygen through the upper tuyeres and an oxygen-inert gas mixture through the lower tuyeres.

To ensure the low temperature preferably it is provided that all process steps are carried out in a temperature range of from 1630 to 1650 ° ^C.

Another improvement provides that in order to obtain the required steel composition on a ladle furnace, silicomanganese and / or ferroaluminium are introduced into the melt.

TWIP (Twinning induced plasticity) or TRIP (Transformation induced plasticity) steel can also be produced.

A practical implementation example provides that the converter for refining ferromanganese serves high-carbon ferromanganese with 75% manganese, 6% carbon and 360 kg (per ton of steel produced) and 530 kg of liquid steel with 0.1% carbon, as well as the required amount of slag-forming moreover, 23.3 kg of carbon are added to the melt, which corresponds to the carbon content in the charge at the level of 2.6%, while in the process of combined oxygen purging through at least one upper and several lower tuyeres, the carbon content is reduced Xia to about 0.9, and then continuously fed to the melt of about 150 kg of cold product in the previous heat as the coolant and due to the continuous purge of oxygen through the lower tuyeres carbon content is reduced to about 0.05-0.1%.

The smelter used to implement the proposed process for producing steel with a high content of manganese and low carbon content is designed so that the SAF melting tank or shaft furnace and, on the other hand, an oxygen converter for producing carbon steel are located on the upstream side of the converter for refining ferromanganese or an electric furnace, while at the end of the line a ladle-furnace unit is provided.

The drawings show examples of implementation of the invention, which are described in detail below. Shown:

Figure 1 - diagram of the melting process (upper part) and the progress of the decarburization process in time (lower part),

Figure 2 - block image of the process and the indication of additives in the smelter.

Figure 1 shows the implementation of the method of producing steel 1 with a high content of manganese and a low carbon content on the basis of molten iron 2 and molten steel 3, as well as slag-forming 4 (see figure 2 with the formation of slag). The method is carried out by feeding liquid ferromanganese 5 with approximately 6% carbon and liquid steel or carbon steel 3a with approximately 0.1% carbon to converter 6a for refining ferromanganese together with the required amount of slag-forming 4. Then, by combined blowing with oxygen 7 through at least one the upper tuyere 8 and the lower tuyere 9 the carbon content is reduced to 0.7-0.8% carbon. At the same time, a certain amount of cold product from the previous heat sits as a cooler 10. At this stage, the carbon content is reduced to 0.05-0.1% due to continuous purging with oxygen 7 through the lower tuyeres 9.

Due to continuous purging with oxygen 7 or a mixture of 11 oxygen and an inert gas through the lower tuyeres 9 and through the upper tuyere 8, the partial pressure of oxygen can be reduced. All steps of the method are carried out at low temperatures from 1630 to 1650 ° C.

To establish the final composition on the ladle furnace 12, an additive in the melt 13 of silicomanganese and / or ferroaluminium is provided.

The smelter for producing steel 1 with a high content of manganese and low carbon content operates according to FIG. 2 with a supply of 14 cast iron or carbon steel, as well as slag-forming 4 and related elements 15. For this, a reduction furnace 16 (with immersion electrodes) or a shaft furnace is provided 17 for producing cast iron 2, or an oxygen converter 6 for producing carbon steel 3a, or an electric furnace 18, which are located in front of the converter 6a for refining ferromanganese. After the converter 6a, a ladle furnace 12 is provided for refining ferromanganese.

A practical example of the implementation of the method according to the invention is that at the first stage, liquid carbon ferromanganese with 75% manganese, 6% carbon and about 380 kg (per ton of steel), as well as 530 kg of liquid steel, are loaded into converter 6a for refining ferromanganese with a carbon content of 0.1% and the required amount of slag-forming 4, while in the melt 13 serves 23.3 kg of carbon, which corresponds to the carbon content in the charge of 2.6%. In a second step, a combined oxygen purge is carried out through at least one upper tuyere 8 and a plurality of lower tuyeres 0 to reduce the carbon content to 0.7%. In the third stage, approximately 150 kg (per tonne of steel) of the cold product from the previous melting is continuously fed as a cooler 10. In the fourth stage, purging through the lower tuyeres 9 with a mixture of 11 oxygen and inert gas is carried out (inert gas serves to protect the tuyeres and provides mixing) carbon reduction to about 0.1%.

The final composition (TWIP or TRIP steels) is obtained by the addition of light elements (aluminum, silicon, etc.), so that integrated steelmaking provides steel 1 with a high content of manganese and low carbon and with the addition of aluminum and silicon and etc.

Designation List

one high manganese and low carbon steel 2 molten iron 3 liquid steel 3a liquid carbon steel four slag-forming 5 liquid ferromanganese 6 oxygen converter 6a ferromanganese refining converter 7 oxygen 8 top lance 9 bottom tuyere 10 cooler eleven mixture of oxygen and inert gas 12 ladle furnace 13 melt fourteen cast iron or carbon steel feed fifteen related items 16 reduction furnace (SAF) 17 shaft furnace eighteen electric furnace

Claims (5)

1. The method of producing steel with a high content of manganese and low carbon from molten iron (2) or liquid steel (3) and slag-forming, characterized in that the supply of liquid ferromanganese (5) with a carbon content of about 6% and liquid steel (3 , 3a) with a carbon content of about 0.1% or molten iron into a converter (6a) for refining ferromanganese together with the necessary amount of slag-forming materials (4), reduce the carbon content in the melt to 0.7-0.8% by means of combined oxygen blowing ( 7) through the upper (8) and lower s (9) of the lance is supplied to a number of previous heat cold product as a cooler (10) and reduce the carbon content of the melt to about 0.05-0.1% by continuous blowing of oxygen (7) through the bottom tuyeres (9). 2. The method according to claim 1, characterized in that the partial pressure is reduced by combined purging with oxygen (7) through the upper tuyere (8) and a mixture (11) of oxygen and inert gas through the lower tuyeres (9). 3. The method according to any one of claims 1 and 2, characterized in that all the steps of the method for producing steel are carried out in the temperature range from 1630 to 1650 ° C. 4. The method according to any one of claims 1 and 2, characterized in that to obtain the final chemical composition of the steel, silicomanganese and / or ferroaluminium is supplied to the melt (13) in a ladle furnace (12). 5. A smelter for producing steel with a high content of manganese and low carbon from molten iron or liquid steel and slag-forming materials, containing a converter (6a) for refining ferromanganese, and a reduction furnace (16) located in front of the converter (6a) for ferromanganese, a shaft a furnace (17) for producing cast iron (2) or an oxygen converter (6) for producing carbon steel (3a), or an electric furnace (18), moreover, after the converter (6a) for refining ferromanganese, a ladle furnace (12) is provided, characterized in what lavilnaya unit is designed for implementing the method according to claims 1-4.

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